const str = 'hello'
const num = 12312321
const boolean = true
const u = undefined
const n = null

const s = Symbol(1)
const s2 = Symbol(1)

const b = 123123131231n
const arr = ['a', 'b', 1, 2]
// arr[0]

const obj = {
  name: '小明',
  age: 18,
  like: ['running', 'rap'],
  info: {
    city: '南昌',
    girlfriend: 3
  }
}

class Person {

}